1. Bean 的生命周期回调
单实例 bean 对象：在容器启动的时候创建对象，在容器关闭的时候销毁对象
多实例 bean 对象：在每次获取的时候创建对象，容器不会调用销毁方法
2. 初始化和销毁方法
代码已经上传至 https://github.com/masteryourself-tutorial/tutorial-spring ，详见
tutorial-spring-framework/tutorial-spring-framework-lifecycle工程
2.1 @Bean 实现
1. Student
public class Student {
public Student() {
System.out.println("student constructor");
}
public void initMethod() {
System.out.println("student initMethod");
}
public void destroyMethod() {
System.out.println("student destroyMethod");
}
}
2. SpringConfig
@Configuration
@Import(ExtBeanPostProcessor.class)
public class SpringConfig {
@Bean(initMethod = "initMethod", destroyMethod = "destroyMethod")
public Student student() {
return new Student();
}
@Bean
public Teacher teacher() {
return new Teacher();
}
@Bean
public Principal principal() {
return new Principal();
}
}
2.2 InitializingBean & DisposableBean 接口
1. Teacher
public class Teacher implements InitializingBean, DisposableBean {
public Teacher() {
System.out.println("teacher constructor");
}
@Override
public void afterPropertiesSet() throws Exception {
System.out.println("teacher afterPropertiesSet");
}
@Override
public void destroy() throws Exception {
System.out.println("teacher destroy");
}
}
2.3 @PostConstruct & @PreDestroy 注解
1. Principal
public class Principal {
public Principal() {
System.out.println("principal constructor");
}
@PostConstruct
public void postConstruct() {
System.out.println("principal postConstruct");
}
@PreDestroy
public void preDestroy() {
System.out.println("principal preDestroy");
}
}
2.4 BeanPostProcessor
1. ExtBeanPostProcessor
public class ExtBeanPostProcessor implements BeanPostProcessor {
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
if (bean instanceof Student || bean instanceof Teacher || bean instanceof Principal) {
System.out.println(String.format("%s =================>>>>>>>>>>>>> postProcessBeforeInitialization", beanName));
}
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
if (bean instanceof Student || bean instanceof Teacher || bean instanceof Principal) {
System.out.println(String.format("%s =================>>>>>>>>>>>>> postProcessAfterInitialization", beanName));
}
return bean;
}
}
